Calcium aluminate cements

[citation needed] The method of making cement from limestone (CaCO3) and low-silica bauxite (Al2O3) was patented in France in 1908 by Bied of the Pavin de Lafarge Company.

FONDAG cement is a mix of up to 40 percent alumina, and is stable at high temperatures and thermal cycling from −184–1,093 °C (−300–2,000 °F; 89–1,400 K; 160–2,500 °R)[4] CAC cement invented in 1908 by Bied[2] is sulfate-free and hardens to give mainly hydrated calcium aluminates or carboaluminates (AFm phases: Aluminium Ferrite mono-substituted phases), sometimes accompanied with C–S–H as a minor component, while Ca(OH)2 (portlandite) is absent.

[7] Constituents of some typical formulations include: The mineral phases all take the form of solid solutions with somewhat variable compositions.

[8][9] The more elevated temperature explains a part of its higher production costs than for the clinker of ordinary Portland cement sintered at 1450 °C.

[citation needed] The liquified mixture cools to a vesicular, basalt-like clinker which is ground alone to produce the finished product.

[citation needed] During the cement setting, the reactive aluminates react with water initially to form a mixture of hydrated phases expressed hereunder in normal oxide notation and also abbreviated in the more compact cement chemist notation (CCN) (CaO = C; Al2O3 = A; H2O = H; and SiO2 = S): the amounts of each is depending upon the curing temperature.

[citation needed] The first two hydrates subsequently decompose to a mixture of 3 CaO · Al2O3 · 6 H2O, Al(OH)3 gel, and water, this process being called "conversion".

[10] The inappropriate use of calcium aluminate cements as a common construction material without special precautions has led to structural stability problems in buildings.

[13] Because of their relatively high cost and delicate implementation, calcium aluminate cements are used in a number of restricted applications where performance achieved justifies costs:[3][citation needed] The biogenic corrosion resistance of calcium aluminate cements is used today in three main applications:[citation needed]